This invention relates generally to lithographic printing presses and more particular concerns a method and apparatus for evaporating excess dampening fluid which infiltrates the ink train during the lithographic printing process.
The inevitable infiltration by dampening fluid into the ink train system of lithographic printing presses is well known in the art. With the virtual elimination of alcohol as a drying agent, the problem of infiltration has been aggravated by the use of alcohol substitutes which, unlike alcohol, do not indicate that infiltration has occurred until extensive damage is already sustained. The presence of dampening fluid in the ink train adversely affects both image quality and color consistency, and when left uncorrected can result in ruined paper and contamination of the ink fountain.
Previous attempts to eliminate dampening fluid from the ink train of lithographic printing presses have proved costly, complex, and generally involve elaborate plumbing networks which pipe air from external air compressors to air jet manifolds or nozzles which direct streams of air to impinge against inker rollers in the printing press in an effort to evaporate excess dampening fluid. These complex assemblies are inherently noisy and, in addition, have a limited capacity to supply a large volume of air. Typical systems are disclosed in U.S. Pat. No. 4,624,689 entitled "DEHYDRATION APPARATUS FOR PRINTING PRESS INKING SYSTEM" issued Jun. 25, 1985 to Milton R. Lemaster, and U.S. Pat. No. 4,452,139 entitled "DAMPENING FLUID EVAPORATOR AND METHOD" issued Jun. 5, 1984 to Dahlgren et al.
The use of air compressor units for delivering pressurized air to jet manifolds or nozzles within the printing press is expensive in terms of power consumption, floor space, and plumbing costs. Further, air bars and manifolds sometimes limit access to the rollers in the press.
With the discovery of the present invention substantial improvements have been made in the elimination of dampening fluid in lithographic printing presses: reductions in cost; ease of installation; virtual elimination of noise; and delivery of a high volume of air at a variable speed.